Refrigeration system with accumulator

ABSTRACT

A REFRIGERATION SYSTEM HAS A COMPRESSOR, A CONDENSER, A TUBE AROUND AN ACCUMULATOR, SUBCOOLING CONTROL VALVE, AN EVAPORATOR, AND THE ACCUMULATOR CONNECTED IN SERIES IN THE ORDER NAMED. THE HEAT EXCHANGE BETWEEN THE HIGH PRESSURE LIQUID FLOWING THROUGH THE TUBE AROUND THE ACCUMULATOR AND THE LIQUID WITHIN THE ACCUMULATOR EVAPORATES EXCESS LIQUID FLOWING FROM THE EVAPORATOR INTO THE ACCUMULATOR, THE HIGH PRESSURE LIQUID BEING SUBCOOLED BY THIS HEAT EXCHANGE. THIS SUBCOOLING PLUS THAT PROVIDED BY THE SUBCOOLING CONTROL VALVE SO INCREASE THE REFRIGERATION EFFECT THAT THE SUBCOOLING CONTROL VALVE OVERFEEDS THE EVAPORATOR.

3,552,140 REFRIGERATION SYSTEM WITH ACCUMULATOR Robert T. Palmer, Sharon, Mass., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 19, 1968, Ser. No. 785,095 Int. Cl. F25b 13/00 US. Cl. 62-324 3 Claims ABSTRACT OF THE DISCLOSURE A refrigeration system has a compressor, a condenser, a tube around an accumulator, a subcooling control valve, an evaporator, and the accumulator connected in series in 'the order named. The heat exchange between the high pressure liquid flowing through the tube around the accumulator and the liquid within the accumulator evaporates excess liquid flowing from the evaporator into the accumulator, the high pressure liquid being subcooled by this heat exchange. This subcooling plus that provided by the subcooling control valve so increases the refrigeration effect that the subcooling control valve overfeeds the evaporator.

BACKGROUND OF THE INVENTION The field of the invention is refrigeration systems in which evaporators are overfed with refrigerant, and in which accumulators are provided for receiving the excess liquid from the evaporators. The US. Pat No. 3,264,837 of J. R. Harnish discloses a refrigeration system which is overcharged with refrigerant so that an accumulator has at all times a quantity of refrigerant liquid therein; in which an evaporator is overfed so that refrigerant liquid flows from it into the accumulator, and in which the excess refrigerant liquid is evaporated by heat from high pressure liquid flowing through a coil within the accumulator. Such coils within such accumulators require relatively large and expensive accumulators, and require relatively large charges of refrigerant. Attempts have been made to dispense with such a coil within an accumulator by wrapping a coil around an accumulator as disclosed in the US. Pat. No. 3,350,898, and by using a heat exchanger between an evaporator and an accumulator as disclosed in the Harnish-Lessley application, Ser. No. 682,149, filed Nov. 13, 1967, now Pat. No. 3,423,954. Such attempts have not been entirely successful due to the poor heat exchange between the high pressure liquid and the liquid to be evaporated.

This invention provides a tube around an accumulator through which high pressure liquid is flowed in contact with the outer surface of the accumulator, such tube being so arranged and constructed that there is sufficient heat exchange surface to evaporate the excess liquid flowing into the accumulator.

SUMMARY OF THE INVENTION A refrigeration system has a compressor, a condenser, a liquid tube, a tube around an accumulator, a subcooling control valve operating as an expansion valve, an evaporator, the accumulator, and a suction gas tube connected in series in the order named. The suction gas and liquid tubes have portions in heat exchange contact. The system is overcharged with refrigerant so that there is always a quantity of refrigerant liquid within the accumulator. The subcooling control valve overfeeds the evaporator so that refrigerant liquid and gas flow into the accumulator while providing subcooling of the high pressure refrigerant liquid. The heat exchange between the high pressure liquid flowing through the tube around the accumulator and the liquid within the latter, evaporates the excess refrigerant United States Patent Office Patented Jan. 5, 1971 liquid flowing from the evaporator, the high pressure liquid being further subcooled by this heat exchange, and the heat exchange between the high pressure liquid within the liquid tube and the refrigerant flowing within the suction gas tube, evaporates any refrigerant liquid flowing from the accumulator into the suction gas tube, the high pressure liquid being further subcooled by this heat exchange. The large amount of subcooling so greatly increases the refrigerating effect that the subcooling control valve is able to overfeed the evaporator without requiring a liquid pump, even at very low outdoor temperatures.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a diagrammatic view of a heat pump embodying this invention, with an accuculator, and a heat exchange tube around the accumulator shown in section.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, refrigerant compressor C is connected by discharge gas tube 10 to a conventional reversal valve RV which is connected by tube 11 to outdoor coil 00, by tube 12 to indoor coil IC, and by tube 13 to the interior of accumulator 14. The coil 0C is connected by tube 15 to check-valve manifold 16, the details of which are disclosed in the US. Pat. No. 3,299,661. The manifold 16 is connected by tube 18 to the indoor coil IC, and by liquid tube 20 to the top of tube 21 around the accumulator 14 at one end of the tube 21. The bottom of the tube 21 at the other end of the latter is connected by tube 24 to the inlet of subcooling control valve EV which operates as an expansion valve. The outlet of the valve EV is connected by tube 25 to the manifold 16. A metal strap 26 is wound spirally around and in contact with the outer surface of the accumulator 14, and in con tact with the inner surface of the tube 21, and provides a plurality of passes for the liquid flowing through the tube 21 in contact with the outer surface of the accumulator 14. Suction gas tube 28 is connected to the compressor C, and has a U-shaped portion 29 within the accumulator 14. The tube portion 29 has an open upper end 30, and has an oil bleed hole 31 in its bottom. The system is overcharged with refrigerant, for example, 20%, so that there is always a quantity of refrigerant liquid having a substantially constant level 35 within the accumulator 14.

The subcooling control valve EV has a diaphragm chamber 32 connected by capillary tube 33 to thermal bulb 34 in heat exchange contact with the liquid tube 20, and is internally equalized so as to respond to the pressure of the liquid entering it. It responds through the bulb 34 and the capillary tube 33 to the temperature of the high pressure liquid, and maintains a predetermined amount of subcooling of that liquid as disclosed in the previously mentioned Pat. No. 3,264,837. It may be of the type disclosed in that patent or of the type disclosed in the US. Pat. No. 3,367,130.

C'OOL ING OPERATION The solid-line arrows alongside the tubing of the drawing show the direction of refrigerant flow during cooling operation. The reversal valve RV is in its cooling position. Discharge gas from the compressor C flows through the tube 10, the reversal valve RV, and the tube 11 into the outdoor coil OC operating as a condenser coil. Liquid condensed within the coil 0C flows through the tube 15 into the manifold 16, and from the latter through the tube 20 into the heat exchange tube 21. The liquid flows in a plurality of passes between turns of the strap 26 around and in contact with the outer surface of the accumulator 14, and then through the tube 24 into the subcooling control valve EV. Expanded refrigerant flows from the valve EV through the tube 25 into the manifold 16, and from the latter through the tube 18 into the indoor coil IC operating as an evaporator coil. The coil IC is overfed so that refrigerant liquid and gas flow from it through the tube 12, the reversal valve RV, and the tube 13 into the accumulator 14. Gas separated from the liquid within the accumulator 14 flows into the open top of the tube portion 29, and through the suction gas tube 28 into the compressor C.

The subcooling control valve EV provides about F. subcooling of the refrigerant liquid as described in the previously mentioned Pat. No. 3,264,837. The heat exchange between the liquid flowing through the tube 21, and the liquid within the accumulator 14, provides about 45 F. subcooling of the refrigerant liquid. The heat exchange between the suction gas tube 2-8 and the liquid tube 20 evaporates the small amount of refrigerant liquid passing with oil through the oil bleed hole 31 into the suction gas tube, and this heat exchange provides about 4 F. additional subcooling. The large amount of subcooling so greatly increases the refrigerating effect that the coil operating as an evaporator coil is overfed even at low outdoor temperatures without requiring a liquid pump. The excess liquid flowing from the coil operating as an evaporator coil into the accumulator is evaporated by heat from the high pressure liquid flowing through the heat exchange tube 21 so that the level 35 of liquid within the accumulator 14 remains substantially constant during normal operation of the system.

HEATING OPERATION The dashed-line arrows alongside the tubing of the drawing show the direction of refrigerant flow during heating operation. The reversal valve RV is in its heating position. Discharge gas from the compressor C flows through the tube 10, the reversal valve RV and the tube 12 into the indoor coil IC operating as a condenser coil. Liquid flows from the coil IC through the tube 18, the manifold 16, the liquid tube 20, the tube 21 around the accumulator 14, and the tube 24 into the subcooling control valve EV. Expanded refrigerant flows from the valve EV through the tube 25, the manifold 16, and the tube into the outdoor coil 0C operating as an evaporator coil. The latter is overfed, and refrigerant liquid and gas flow from it through the tube 11, the reversal valve RV, and the tube 13 into the accumulator 14. Gas separated from the liquid within the accumulator flows through the suction gas tube 28 to the compressor C. Evaporation of refrigerant liquid by heat from the high pressure liquid, and subcooling of the latter occur as described in the foregoing in connection with cooling operation.

During both cooling and heating operation, the high pressure liquid flowing around and lengthwise of the accumulator in contact with its outer surface, provides sufficient heat to evaporate the excess refrigerant liquid flowing from the coil 0C or IC operating as an evaporator coil, without requiring the previously required coil within the accumulator.

I claim:

1. Heat pump comprising a refrigerant compressor, reversal means, a discharge gas tube connecting said means to said compressor, an outdoor coil, a second tube connecting said means to said coil, an indoor coil, a third tube connecting said means to said indoor coil, an accumulator, an expansion valve, means including a liquid tube and heat exchange means for connecting the one of said coils that is operating as a condenser coil to the inlet of said expansion valve, means including a fifth tube for connecting said reversal means to said accumulator, a suction gas tube connecting said accumulator to said compressor, means including a seventh tube for connecting the outlet of said expansion valve to the one of said coils that is operating as an evaporator coil, said reversal means in cooling position routing discharge gas through said second tube to said outdoor coil operating as a condenser coil, and routing refrigerant from said indoor coil operating as an evaporator coil through said third and fifth tubes into said accumulator, said reversal means in heating position routing discharge gas through said third tube into said indoor coil operating as a condenser coil, and routing refrigerant from said outdoor coil operating as an evaporator coil through said second and fifth tubes into said accumulator, said heat pump being overcharged with refrigerant so that there is always a quantity of refrigerant liquid within said accumulator, means for adjusting said expansion valve to overfeed the one of said coils that is operating as an evaporator coil so that refrigerant liquid and gas flow through said fifth tube into said accumulator, said heat exchange means comprising means for flowing high pressure liquid around and lengthwise of said accumulator in contact with the outer surface of said accumulator for evaporating with heat from said high pressure liquid, refrigerant liquid within said accumulator at substantially the rate at which refrigerant liquid flows into said accumulator from the one of said coils that is operating as an evaporator coil.

2. A heat pump as claimed in claim 1 in which said heat exchange means comprises a tube around said accumulator, and comprises means for causing high pressure liquid flowing through said last mentioned tube to flow in a plurality of passes around and in contact with said outer surface of said accumulator.

3. A heat pump as claimed in claim 2 in which said last mentioned means comprises a strap wound spirally around said accumulator in contact with said outer surface of said accumulator.

References Cited UNITED STATES PATENTS 2,116,100 5/ 1938 Cracknell 62-'205 2,472,729 6/1949 Sidell 62-83 2,885,868 5/1959 Radcliffe 625l1 2,985,435 5/1961 Gross 163-156 WILLIAM E. WAYNER, Primary Examiner US. Cl. X.R. 62503 

